Switching device



Feb. 2, 1965 H. D. MORRIS 'swITcHING DEVICE 3 Sheets-Sheet 2 Filed Sept. 2. 1960 w mm Imlmnrmm wm mD. .w M f d y JV ,j hws W M w mw Feb. 2, 1965 H. D. MORRIS 3,168,680

SWITCHING DEVICE Filed Sept. 2, 1960 3 Sheets-Sheet 3 #am/cf D. Marr/s.

United States Patent fhce SWi-friitm Hamid Morris, alii., ass-goor to Systron- Donner Corporation, eneord, aii., a corporation oi Cahier-nia i'iied This invention relates to a switching device and more particularly to a switching device for conducting a switching operation at a predetermined acceleration or velocity.

ln the operation of a missile, it is often necessary to actuate a switch contact as the input acceleration or velocity reaches a predetermined value. Switching devices heretofore provided for such a purpose have not been completely satisfactory because their operation has not been independent of the great amount of vibration which occurs in the missile duringr the time that it is accelerating. The problem has been complicated by the fact that the vibration of the missile during this period of time imposes shock and vibration forces on the switching device which are gener-ally greater than the force upon which the device is supposed to actuate. Attempts have been made to average out the vibration by damping the accelerometer utilized in such devices. This has not been completely satisfactory because, as is well known to those skilled in the art, the use or such damping reduces the sensitivity of the device. In particular, such damping `increases the time required for recovery from overload and greatly increases the time required for checking out the operation of the switching device before launching of the missile. in addition, when oil is used for damping, the viscosity of the oil changes greatly under the variations in temperature which are encountered by the device. rhere is, therefore, need for a new and improved switching device which can be utilized for accomplishing a switching operation when the input acceleration reaches a predetermined value or when the velocity reaches a predetermined value.

In general, it is an object of the present invention t provide a switching device which will switch accurately at a predetermined acceleration or a predetermined Velocity.

Another obiect of the invention is to provide a switching device of the above character which will switch accurately substantially independent of shock or vibration applied to the device.

Another object of the invention is to provide a switching device of the above character which has very high reliability.

Another object of the invention is to provide a switching device of the above character which will always operate in a predetermined time interval in the presence of a predetermined average acceleration or predetermined average velocity.

Another object of the invention is to provide a switching device of the above character which is substantially independent of variations in temperature.

Additional objects and features of the invention will appear from the following description in which the preferred embodiments are set forth in detail in conjunction with the accompanying drawings.

Referring to the drawings:

FiGURE l is a block diagram of a switching device incorporatinf7 the present invention.

FIGURES 2, 3, 4 and 5 are each block diagrams of .other embodiments of my switching device.

FGURE 6 is `a detailed circuit diagram of the switching device shown in block diagram form in FIGURE 3.

FGURE 7 is a portion of ya detailed circuit diagram showing a modication of the switching device shown in FIGURE 6.

3,353,539 Patented Feb. 2, 1965 FIGURE 8 is a portion of a detailed circuit diagram showing another modification of the switching device shown in FIGURE 6.

In general, my switching device consists of means for measuring acceleration, reference means, and decision means connected to the means for measuring acceleration and the reference means for producing a signal when the output from the means for measuring acceleration is greater or less than the output from the reference means.

in FIGURE l, I have shown in block diagram form one embodiment of my switching device. It consists of an acceleroineter 11 which is oi the type described in my copending application Serial No. 794,487, filed February 4, 1959, and entitled Position Detecting Transducer, now Patent No. 3,974,279. The accelerorneter provides an outA ut which is determined by the acceleration applied to it. This output is supplied to a decision circuit i2 which utilizes a reference 1S. The decision circuit 12 is, in erect, like a voltage comparator as hereinafter described and provides no output unless the input supplied to it by the accelerometer 1i. exceeds the reference 13. it is thus apparent that the reference i3 can be adjusted to a value which represents the predetermined acceleration at which it is desired to cause operation of the switching device. rhus, when the output from the accelcrometer 1i exceeds that of the reference 13, a signal will `be supplied to the amplir'ler 14 which amplies the output and causes energization of the coil of the relay 16 to cause actuation of the contacts ofthe relay.

in the embodiment shown in FIGURE l, the iiltering has been restricted to mechanical iiltering which is applied to the accelerometer 1i. The mechanism within the accelerometer ii has been damped by filling the accelerometer with oil. Such a switching device has operated very satisfactorily.

Another embodiment of my invention is shown in FlG- URE 2. it is similar to the embodiment in FIGURE l with the exception that an RC lter 13 is interposed between the accelerometer 11 and the decision circuit 12. The RC iilter l is of a conventional passive type and is provided for the purpose of supplementing the filtering provided by the mechanical filtering in the accelerometer The RC filter 13 ensures that the vibration or shock forces applied to the switching device are attenuated sufficiently so that they do not cause premature operation of the switching device.

ln FIGURE 3 is shown another embodiment of my switching device in which the output of the accelerometer 1.1 is suppiied to a decision circuit 19 utilizing a reference 21. The output of the decision circuit 19 is supplied to an integrator 22, the output of which is supplied to a zero comparator 23. The output of the comparator 23 is supplied to the ampliiier 14 which is connected to the relay 16.

The integrator 22 is used to provide a time delay so that the decision circuit 19 must supply a signal of a certain type as hereinafter explained for a predetermined period or time before the relay 16 is operated. The operation of the switching device shown in FIGURE 3 will be described in detail in conjunction with the detailed circuit diagram shown in FIGURE 6.

Another embodiment of my switching device is shown in FIGURE 4 in which the output of the accelerometer 11 is supplied to a second-order filter 26. The second-order iilter 26 is an electronic lter of the type described in my copending application Serial No. 791,216, led February 4, i959, and entitled Electronic Filter, now Patent No. 3,122,714. This filter is of the active type rather than the passive type shown in FIGURE 2. Such filters have displayed very desirable characteristics and are particularly adapted for use in my switching device. For example, they can be readily designed to eliminate all freannesso4 quencies above two cycles per second thereby essentially eliminating all vibrational components in the acceleration signal. The output of the filter 26 is supplied to the decision circuit 27 which utilizes a reference 28.' The output of the decision circuit is supplied to the amplifier 14 which is connected to the relay 16. The switching device shown in FIGURE 4 has an advantage over the one shown in FIGURE 3 because there is not as much time delay associated with the circuit as with the circuit shown in FIGURE 3.

In FIGURE 5 is shown another embodiment of my invention showing how the circuits in FIGURES l, 2, 3 and 4 can be utilized as velocity switches instead of acceleration switches. The output of an accelerometer Il is supplied to an integrator 29 which serves a dual function. The integrator 29 provides filtering and, in addition, integrates the output of the accelerometer il to provide a signal which represents velocity rather than acceleration. The signal representing velocity is supplied to a decision circuit 3l utilizing a reference 32. As soon as the velocity signal exceeds the reference 32, an output is supplied by the decision circuit 3l to the relay amplifier I4 which operates the Vrelay 16.

In all of the embodiments in FIGURES l through 5, it is preferable to eliminate or minimize vibrational cornponents down to five cycles per second. However, it is only in the embodiment shown in FIGURE 1 that relatively heavy damping is required in the accelerometer itself. In the embodiment shown in FIGURE l, this damping is accomplished by utilizing a relatively heavy fluid in the accelerometer. In each of the additional embodiments, additional filtering means is provided soy that heavy damping is not required in the accelerometer. In the embodiments in FIGURES 2 through 5, filtering is actually accomplished by cascading the filtering means after the accelerometer. When such is the case, a relatively wide band accelerometer can be used with normal damping with the primary characteristics of the switching device for rejection of vibration being determined by the filter rather than by the damping provided in the accelerometer. This makes the rejection of vibration relatively independent of temperature which is not the case when heavy oil damping is utilized in the accelerometer because as is well known to those skilled in the art, the viscosity of oil changes greatly with the changes in tem- .perature If desired, all of the accelerorneters can be oil filled. However, where the oil is not relied upon for providing damping, the oil can be relatively light. T he oil in such a case is provided to make the accelerometer more rugged with only nominal independence of vibration.

Although a relay i6 and relay amplifier 14 have been shownV in each of the block diagrams in FIGURES l through 5, it is readily apparent that, if desired, other types of switching means can be utilized to accomplish the same result. For example, if desired, a semiconductor switch such as a four-layer semi-conductor diode can be utilized. As is well known to those skilled inthe art, such a diode is voltage sensitive and can provide a pulse for the actuation of a device.

As explained previously, FIGURE 6 is a circuit diagram of the switching device shown in block diagram form in FIGURE 3. The accelerometer 1li is shown in block diagram form because it is described in detail in my copending application Serial No. 794,487, filed February 4, 1959. The accelerometer l1 is connected to a suitable D.C. supply such as +30 volts D.C. by a line 36. It is also connected to ground by a line 37. The signal output of the accelerometer is supplied on the conductor 38 to the decision circuit 19. A conductor 39 completes the load circuit to the accelerometer.

A power supply and regulator 41 is provided as a part Vof the switching device and consists of a Zener diode `CRltl which produces a first voltage on line d2 of a suitable value such as a plus 8 volts. A transistor Qliil pro` duces a second voltage on line 43 of a suitable value such .as a plus 1S volts. This latter or second voltage is a regulated voltage which is regulated by the transistor Qlll. The base of the transistor Qltil is controlled by a Zener reference diode CRil. This Zener diode operates so that the output voltage on line 43 is maintained substantially constant. For example, if the voltage at the collector of the transistor Qllil tends to rise, the Zener diode CRII increases the voltage on the base of the transistor Qlill and thus brings the voltage on the collector back to the normal or the predetermined second voltage.

It is therefore, apparent from the foregoing description that there is present in the circuitry in FIGURE 6, ground which appears on line 37, a rst voltage which appears on line 42, a second voltage which appears on line 43, and a third voltage which is the D.-C. supply voltage which appears on line 36.

Te Zener diode CRlilZ serves as a shunt regulator because it is in parallel with the output load of the power supply as is the transistor Qtll.

All of the current for the power supply and regulator comes in through the resistor Rim connected to the D.C. supply line 36. The current passing through the transistor Qltll and the load in parallel with it which provides a majority of the operating current for keeping the Zener diode CRlilZ in an operating condition.

The resistors Rllltl and Rltl7 form a divider network which inserts a voltage into the regulator and power supply to make the regulator and power supply 4l independent of line voltage. For example, if the D.C. voltage on line 36 should, for example, drop from a +30 volts to a +27 volts, the voltage on the line 43 would also have a tendency to drop in voltage. When this occurs, the voltage fedthrough the divider consisting 'of the resistors R119 and R167 would cause the voltage on the base Qlfll to drop even further than it would normally and thereby would return the output voltage on the collector back to its normal predetermined value. The divider network therefore, compensates for changes in line voltage to maintain the voltages within the switching device essentially independent of the incoming line voltage.

Resistor Rlill is a load resistor for the accelerometer il and is normally adjusted to calibrate the acceleration switch for the proper switching point. The accelerometer is normally oriented so that the voltage on the left-hand side of the resistor Ridi as viewed in FIGURE 6 goes negative with respect to the right side upon acceleration in a forward direction.

When the acceleration equals and exceeds the tripping or switching point of the succeeding amplifiers, as hereinafter explained, the voltage on the left-hand side of the resistor R101 comes to the point where resistor R163 and diode CRIGS conduct to the line 42 carrying the first voltage and provide increased current for the accelerometer. The resistor Rllllt'l and the diode CRltl, therefore, provide overload capacity for the switching device so that the accelerorneter il will pull in more quickly, that is, the increased current will act upon the restoring coil to move the paddle more quickly to the desired position and operate in a higher acceleration or higher G environment than the switching point for which the switching device is set. The resistor R163 and the diode CRlS, therefore, provide a switching device which gives a greatly increased range to the accelerometer. It, in effect, makes it possible to use a much larger voltage to represent the normal switching point of the switching device. Upon reaching the switching point, the remainder of the range of the switching device is compressed into the remainder of the voltage available. In

actuality, the switching range is magnified and the other range, which is provided only for overload capacity, is compressed. The resistor Riil and the diode CR103,

tti

therefore, makes possible very accurate operation at the switching point of the switching device.

The resistor R109 in the power supply and regulator 41 provides a path for current tiow to keep the Zener diode CR101 in a reasonable operating condition. For example, if it is assumed that the current through the correction divider network comprised of resistors R107 and R111) is small in comparison, then the primary current flowing through the Zener diode CRllil will be supplied by the resistor R109.

The decision circuit 19 consists of the transistor (2261 and its associated components. When the acceleration is zero, the current throughout the transistor Q2il1 will be zero. When this is true, the current ilow through conductors 33 and 39 will also be zero. Thus, when there is no acceleration, the voltage on conductor 38 will be equal to the second voltage which is on line 43.

The emitter of the transistor Q2tl1 is biased to very near the voltage level appearing on the conductor 42 by the biasing network consisting of the resistor Rltl and diodes CRliand CRltl. For example, in one embodiment, the transistor Q261 was biased approximately 1.2 volts above the 8 volts on line 42 with .6 of a volt drop between emitter and the base of the transistor (2261 so that the base of the transistor Q2li1 was approximately 8.6 volts above ground.

A diode network consisting of first and second diodes CR2tl1, CR202 and resistor R2ti3 is provided and serves as a gate so that the current flowing through resistor R263 will be supplied either by CRZGI or CRZtiZ depending upon which diode is returned to the higher voltage source. Thus, for example, if the voltage on line 3S is at +18 volts (the condition when there is no acceleration) or at the same voltage as the second reference voltage, then this voltage is obviously larger than the first reference voltage (approximately 8.6 volts) appearing on the base of the transistor Q2il1. Thus, when this is the condition, the current owing in resistor R293 will be supplied by diode CRZlll because diode CR2ii2 is reverse biased and will be non-conducting. For that reason, there will be no current flowing in the base of the transistor Q2ii1. When there is no current flowing in Qtli, there will be no current flowing in the resistor R201 in the collector circuit of the transistor Q2il1.

The resistor R2ti1 in the collector circuit of the transistor Q2tl1 is connected to a conductor 46 which is connected to the integrator 22. It is also connected to a resistor R2il2 which is connected to the ground lead 37. The integrator 22 is actually an integrating amplifier and is comprised of the transistor Q202 and the capacitor C251 which is connected between the collector and base of transistor (2292. The collector of the transistor (2202 is connected to the second reference voltage appearing on line 43 through a load resistor R1ti.

The Zero comparator 23 consists of the transistor Q1tl2, the collector load resistor R164, and the diode net- /ork consisting of tirst and second diodes CR1G4, CRltlS and the resistor R163. The amplier 14 consists of the transistor Qlti and the capacitor C101 connected between the collector and base elements of the transistor. Capacitor C101 serves to suppress spurious amplifier oscillations. The emitter of the transistor Q1i3 is connected to the D.C. supply line 36, whereas the collector is connected to one side of the winding 51 of the Vrelay 16. The other side of the winding is connected to the groundlead 37 as shown. The relay 15 is provided with a plurality of contacts which have been numbered 1 through 6. As can be seen, certain of the contacts are normally open, whereas others of the contacts are normally closed. The switching device is provided with a plurality of test terminals S3 and 54. The resistor R111 permits a predetermined current flow representing an acceleration signal greater than that required to meet the switching point when the line 54- is grounded to permit testing of the acceleration switch without physically accelerating it.

Operation ot the switching device shown in FIGURE 6 may now be brielly described as follows. Let it be assumed that the switching device is of a type which operates on decreasing acceleration. The initial starting condition of all the components is as follows, that is, when there is maximum acceleration applied to the device, transistor Q2ti1 is on, transistor Q202 is on and in a reset condition. Transistors Q1t2 and Q103 are turned off because the driving current for Q102 can come only from the D.C. supply line 36 through the resistor R103. Current will llow through the resistor R103, diode CR1ti4 and transistor Q202 to apply reverse bias to the diode CRltiS and prevent current ilow to the base of transistor (2162.

When the acceleronieter 11 has an output which drops below the predetermined switching level, QEtil will he turned oit and the two transistors Q2tr1 and QZSZ wiil be turned on with Qtil regulating the second reference voltage appearing on line 43.

As the vehicle carrying the switching device loses forward acceleration, the voltage on line 38 will begin rising from near ground towards the switching point which is in the vicinity of the voltage appearing on the line 42 since the transistor amplifier (22@1 is biased to very near this voltage level by the biasing network consisting of the resistor R165, and the diodes CR106 and CR107. As the voltage on line 38 continues to increase (the current decreases) as the accelerorneter decreases its output, the differential in voltage supplied to the two diodes @R2 i and CR212 decreases. When the voltage applied to the diode CFK/3&1 rises above the lirst reference voltappiied to diode CREZ, the current supply for the vresistor will come through the diode CR2$1 to remove the drive from transistor Qbl. This will reverse the drive applied to the transistor (2232 due to the lack oi a saturating input from the resistor RZSE. Current will flow away from the input of the transistor QZZ, that is, away from the base to ground through the resistor R292. The transistor will be turned oil because of the current ilowing through resistor R232 as hereinafter described.

The collector of the transistor Q2f32 will, therefore, begin running up on a ramp function of voltage searching for the second reference voltage appearing on the line 43. This voltage is stored in the capacitor Cdl. If this condition were uninterrupted, the collector would rise in vo.tage until it reached the plus 18 volts. However, as the collector of the transistor Q20?. passes through the reference voltage represented by the base voltage or zero reference voltage of the transistor Q1ii2, which is the same as the base voltage on transistor QZtil, the current will suddeniy switch from flowing through the diode GRIMM to iiowing through the diode CRIS into the base oi the transistor QillZ. This current is multiplied by the gain of the transistor Qitl2 and is supplied to the transistor (2163 which ampliiies the current to a point so that the relay 16 can be operated very easily.

ln the foregoing description of the operation of my switching device it should be remembered that although the accelerometer 11 produces a slowly changing signal, or in other words, an output which is directly proportional to the applied acceleration, there is superimposed upon this slowly changing output the effects due to vibration and shock which will be in the form of relatively high frequency voltage excursions above and below the linear output voltage of the accelerometer. This output of the accelerometer is supplied to the decision circuit 19 which continuously compares the accelerometer output with the reference voltage which is the voltage appearing on the base of the transistor QZtll. When the accelerometer output is below the reference voltage, the transistor (2291 is conducting and supplies a constant positive output for all accelerations below the reference voltage. When the output from the accelerometer is suiiicient to bring the voltage applied to the diode CRZill above the voltage applied to the diode CRZM, the transistor Qtll of the decision circuit i9 will be turned off, resulting in a constant negative input to the integrator 22 due to current flow in resistor R252. Current flows in resistor 12.2%?. of the inherently constant base to emitter voltage of silicon transistor Q2t2.

Thus, it can be seen that the decision circuit i9 will be switched on and off in accordance with the voltage variations in the output of the accelerometer as applied to the line 38. Each time the diode CRZQ stops conducting, the transistor QZl will begin conducting to cause saturating current to be applied to the transistor Q29?. to cause the decision circuit to be switches off which, in turn, causes discharging of the capacitor C2551. Conduction of QZtil and QZZ represents the reset state and, therefore, this condition can be defined as an ofi condition. As long as the decision circuit 19 spends a greater amount of time oli than it does 011, the charge on capacitor CZl will be dissipated each time and the collector of the transistor C2292 will have to start as substantially zero each time in generating the ramp function of voltage.

in other words, the integrator 22 begins at a reset state which represents negative saturation voltage for the transistor Q. The'input to the integrator when the decision transistor QZT is conducting tells the transistor (2262 to go further into saturation and this continues up to the time the decision circuit reverses and indicates that the vibration superposed upon the linear acceleration signal has begun peaking over the acceleration reference voltage. As this commences to occur, the integrator will begin running upwards towards the switching point during the time that the input wave form exceeds the reference value. The integrator will run back towards zero during the time interval that the signal is below the switching point. This means that the integrator will always end up in the reset condition unless the input waveform stays above the reference voltage for more than 50 percent of the time. When the waveform stays above the reference voltage for more than 5() percent of the time, the integrator will end up with a net value after each cycle and will have essentially the same value as if you were integratingV the average of the input waveform.

Iowever, this is not precisely true because interruptions occur in the integration process as hereinafter explained. The net effect is that as each cycle of input vibration is applied to the decision circuit, the integrator will end up at a higher and higher value until it crosses through zero and actuates the output relay. Until the acceleration signal averages more than 50 percent of the time above the switching point, the integrator 22 will always end up in a reset condition after the applied vibration. This means that the accelerometer can be biased with linear accelerationY by using earths gravity right up to near the switching point. This makes is possible for the switching device to absorb very large values of G caused by shoci: and vibration without affecting the switching point. This is possible because therswitching device realizes that with applied vibration and shock, it is not possible to spend more than half of the time above switching point and for that reason the integrator never ends up with a net value and switching never occurs until the average linear acceleration is above the switching point.

it is only when the decision circuit is spending more than substantially one-halt of its time with the diode CRZel conducting and less than one-half of its time with CREW; conducting, that the integrator has any chance of progressing upwardly and passing through zero to actuate the zero comparator.

As the input acceleration signal causes the `decision circuit 9 to spend more than 50 percent of its tirne above the reference voltage, the integrator will progress uprwardly in the generation of a ramp function of`voltage Valthorrgh not in a steady fashion, but rather in a Zig-zag fashion. This is because the capacitor Ctli is charged for a certain time and then discharged for a shorter length of time. For that reason, a charge gradually builds up on the capacitor C261 so that it is not necessary for the collector to start at Zero voltage or substantially zero voltage each time the transistor QZZ is turned off.

When the collector voltage of the transistor (.2292 passes through the Zero line represented by the zero reference voltage on the base of transistor QltiZ the zero comparator will be operated as hereinbetore described to cause operation ofthe relay le.

From the foregoing, it can be seen that the integrator 22 serves as a type of a time delay to ensure that the acceleration is above the predetermined acceleration for a certain period of time before the contacts are operated.

By way of example, one switching device incorporating the present invention had the following components:

orsi, ores and osea Type 2Ns35.

actuate improperly due to the vibration or shock. It

operated in the correct interval of time in the presence of the predetermined average of linear acceleration. The switching levels of the `device were varied from 0.9 G to 1.5 G and the integrating time required to actuate the output relay was set for various times ranging from 0.2 to 1.5 seconds. lt was found that the switching points could be set very accurately even though great amounts of vibration were present. Thus, for example, it was found that with the above accelerometer it was possible to have the accelerometer set to operate its contacts at 0.9 G or acceleration and not to have the switch actuated by the application of vibration or shock forces or 2O Gs or more.

As hereinbef re explained, in FGURE 6 we have shown a circuit diagram of the switching device which is designed to operate the relay r6 when the acceleration alls below the switching point for which the switching device has been caribrated. It is readily apparent that it may be desirable to provide such a switching device which is designed for operation so that the relay will be energized when the acceleration exceeds the switching point for which the device has been calibrated. Two embodiments for accomplishing an operation of this type are shown in FIGURES 7 and 8. Since it is only necessary to make siight changes in the decision circuit l? of the circuitrshown in FiGURE 6, only the modified den cision circuit has been shown in FIGURES 7 and 8. It should be understood, or" course, that the remaining portion 0f the circuitry shown in FEGURE 6 remains unchanged.

The primary change to be made in the decision circuit is to change the connections to the transistor (229i so that operation occurs without sign inversion. As pointed in the embodiment shown in FGURE 7, a grounded base conguration is utilized for the transistor Qtlll. The diode CRZtlZ connects the base oi the transistor Qtl directly to the reference line The diode CRN? has been eliminated and diode Ci ldd is connected directly to the signal line Tie diode Citl has also been omitted. The diodes and Cliid torni a diode Comparator as hereinafter described.

Operation of this embodiment ot the invention may now be brieiiy described as follows. When the acceleration on the accelerometer is zero, the voltages on lines 38 and d3 are identical. A high voltage is, therefore, applied by the line 38 to the diode CRiti to reverse bias it and to prevent current from iiowing through it from the resistor RMS. The current through the resistor RMS, therefore, flows into the emitter of the transistor Qtl. ince the voltage on line 43 is substantially above the voltage on line da to which the base ot the transistor (2291 is connected through diode CRQZ, transistor will be turned on vigorously and will saturate itself and supply a full positive signal to the transistor (2262 through the resistors R291 and R262. Transistor Qld?. will, therefore, be turned on into a reset condition identical to that described in the embodiment shown in FIGURE 6. Thus, it can be seen that the reset condition, that is, with transistors (2213i and QZZ turned on, results from a zero accelera-.ion condition. Y

As the acceleration signal of the accelerorneter increases, the voltage on line 38 increases in a negative direction from the positive reference voltage (i8 volts) on the line d3. A decreasing voltage in a reverse direction will, therefore, be applied to the diode @G4106 until the voltage on the diode Clrtlo decreases so that it is substantially equal to the voltage on the d2 and there is zero reverse voltage on the diode C3396. There is a vary small voltage drop from the base to the emitter ci the transistor Qldl. As soon as there is zero reverse voltage on the diode Clltld, the diode CRl begins conducting and carries all of the current from the resistor Ril to the accelerometer. This, therefore, removes the current supply for the emitter of the transistor Q Zijl and, therefore, the transistor (2261 is turned -oi immediately upon establishing a zero reverse voltage condition on the diode CRlGb. Turning off the transistor Qill removes the positive supply to transistor QtlZ provided by the collector of the transistor QZiil to also turn oir the transistor (2262.

Upon increasing acceleration and as the voltage on the line 38 increases in a negative direction and exceeds the voltage which is on line 42, the emitter of the transistor Q til is pulled with this voltage. As the emitter of the transistor (220i is pulled along with the voltage, so is the base circuit of the transistor (E291. Therefore, when the voltage on the one side of the diode CRlti is equal to the voltage applied to the diode CRZGZ by the line 42, the diode CRZZ is in effect disconnected from the reference voltage 4.2 and prevents the transistor Qtill from being reverse voltaged.

The operation of the remainder ofthe circuit is identical to that described for FGURE 6. It is, therefore, apparent from the foregoing that in FIGURE 7 is disclosed a device which will switch at a predetermined point with increasing acceleration, whereas the embodiment in FG- URE 6 switches upon reaching a predetermined switching point with decreasing acceleration.

in general, the primary difference between the embodiments in FIGURE 7 and the one shown in FIGURE 6 is that the transistor Qtll is operated as a grounded base amplifier rather than a grounded emitter amplifie-r so that there is an output current in the collector circuit of transistor (226i for accelerations in excess of the reference signal in FiGURE 6 and an output current in the collector circuit of transistor ,2.0i for accelerations less than the refe ence signal.

Another modification of FEGURE 6 is shown in FI"- receso URE 8 which utilizes the same diode comparator circuit which is utilized in FGURE 6. However, in this case, the diode CRT?. is connected to the emitter of the transistor Qffl. The resistor RZS is connected to the line d3 rather than to the ground line 37. r{he base of the transistor Qld-l is connected directly to the reference line d2. Resistor RMS and diodes CRitii and Citi-67 have been elir.- ated.

Operation of the embodiment shown in *iGURE 8 may now be brieiiy described as follows: Assuming that acceleration is zero, the voltage on line 3S is identical to the voltage on line When this is the case, the voltage on line Si; is greater than the voltage applied to the cathode of diode CRZtlZ. A reverse voltage or bias is, therefore, applied to the diode CRT/.iii to render it noncoi-'luctirg For that reason, all of the current from resistor w23 flows through diode CREW into the emitter of the transistor Qdi which is operating in a grounded base conliguration. The transistor @Zilli is, therefore, turned on vigorously to apply a positive signal to the resistors Ridi and R262 and to cause the transistor (2.262 to be turned on. Therefore, both of the transistors QZtll and Qtll are in the reset condition as hereinbefore explained when acceleration is zero.

As the acceleration increases and the voltage on line actually exceeds the voltage on the reference line 42, the current passing through the resistor R263 begins passing through the diode Citll to the acceleroineter. This removes the drive from the transistors C2201 and QZSZ to cause the generation of the ramp voltage by the integrator 2,2 as hereinbefore described in conjunction with FEGURE 6.

As the output voltage from the accelerometer on the line increases beyond the ref nce point determined by the voltage on the reference line d2, the diode CRZbZ is reverse vcltaged or has a reverse voltage applied to it to prevent the transistor QZii from being reverse voltaged by the acceleration signal. The operation of the remainder of the circuitry is identical to that described for FEGURE 6.

Although the circuitry in FlGURF. 6 has been described in coniunction with the block diagram shown in FIGURE 3, the circuitry in FIGURE 6 can be readily altered to produce the circuits shown in FIGURES l, 2, 4 and 5. For example, the circuit shown in FlGURE l can be created merely by removing the decision circuit 19 and the integrator 212 and utilizing the zero comparator 2?: as the decision circuit i2 in FlGURE 1. This zero coniparator, in reality, is also a decision circuit because it comrares the input with zero and gives a yes or no answer to whether or not the zero has been crossed. After removal of these two circuits, the conductor 38 can be connected directly to the diode CR194 to provide the switching device shown in FEGURE l.

With respect to the block diagram shown in FIGURE 2, it would only be necessary to use the circuit just described or FiGURE l and place an RC iilter in series with the accelerorneter so that the output signal from the accelerometer is modified before it is supplied to the zero comparator which forms the decision circuit 12.

The circuit for the block diagram in FIGURE 4 would be similar to that of FlGUiE 2 with the exception that a second order filter would be substituted for the RC filter. The circuit for FiGURE 5 would also be similar to that shown in FlPURE 3 with the exception that the zero comparator 23 would be removed and integrator 22 would be placed ahead of the decision circuit 19 rather than after it.

In the embodiments shown in FIGURES l, 2, 4 and 5 it is readily apparent that, if desired, the switching device can be made to operate upon crossing a predetermined switching point, by decreasing acceleration or by increasing acceleration merely by making certain minor rearrangements as shown in the circuit diagrams in FEGURES 6, 7 and 8. The same would be true for causing a switcharenoso 'i l ing device to actuate upon crossing a predetermined velocity by a decreasing velocity or an increasing velocity.

It is apparent from the foregoing that I have provided a new and improved switching device which will switch accurately at a predetermined acceleration or at a predetermined velocity by either increasing acceleration and velocity or decreasing acceleration and velocity. Such switching operations are readily performed independent of any shocl; and vibratory forces applied to the switching device. Although certain of the circuitry shown has utilized solid state components, it is readily apparent that, if desired, other components such as vacuum tubes can be utilized without departing from the scope of the present invention.

I claim:

1. In a switching device, an accelerometer for measuring acceleration, a decision circuit connected to the accelerometer, the decision circuit including means capable of assuming conducting and nonconducting states, means for supplying a reference to said means capable of assuming conducting and nonconducting states representing a predetermined switching point, said means capable of assuming conduct-ing and nonconducting states assuming one of said states when the output from said accelerometer is on one side of the reference and assuming the other oi said states when said output from the accelerometer passes the reference, integrating means connected to said decision means and serving to generate a ramp function when said means capable of assuming conducting and nonconducting states is in said other of said states and zero comparator means for comparing said ramp function with said reference voltage to determine when said ramp function passes said reference and switching means actuated by said zero comparator as said ramp function passes said reference. Y

2. A switching device as in claim 1 together with means for preventing the application of a reverse bias to said means capable of assuming conducting and nonconducting states.

3. A switching device as in claim 2 wherein said means capable of assuming conducting and nonconducting states is a transistor arranged in a grounded emitter contiguration.

4. A switching device as in claim 2 wherein said means capable of assuming conducting and nonconducting states is a transistor arranged in a grounded base contiguration.

5. In a switching device, an accelerometer for measuring acceleration, a decision circuit connected to the accelerometer, the decision circuit including comparator means in the form of a pair of diodes arranged to conduct in opposite directions, means connecting the output signal voltage of the accelerometer to one of the diodes, means supplying a reference voltage to the other of the diodes,

-means for establishing a complete circuit for the diodes so that the diode with the higher voltage applied thereto 0conducts current and the other diode-with the lower voltage applied thereto does not conduct current, integrating means connected to said decision means serving to generate a ramp function when the output of said accelerometer passes the reference, zero comparator means for comparing said ramp function with said reference to determine when said ramp function equals said reference and switching means actuated by said zero comparator as said ramp function passes said reference.

6. A switching device as in claim 5 wherein said decision circuit includes inverting amplifier means to permit the switching device to be used for actuating the switching means from a decreasing acceleration.

7. A switching device as in claim 5 wherein said decision circuit includes a noninverting ampliiier means to permit said switching device to actuate switching means from an increasing acceleration. Y

8. A switching device as in claim 5 wherein said decision circuit includes a transistor having base, collector and emitter elements with the base of the transistor being connected to the diode to which the reference voltage is connected, the transistor serving to couple the reference voltage to said diode, and wherein the other diode is directly connected to the output of the accelerometer.

9. A switching device as in claim 5 wherein said decision circuit includes a transistor having base, collector and emitter elements and in which the base of the transistor is connected to the diode to which the reference is connected and in which the emitter is connected to the diode to which the output of the accelerometer is connected, the transistor serving to couple the two diodes.

it). A switching device as in cla-im 5 wherein the decision circuit includes a transistor having base, collector and emitter elements and in which the emitter element is connected to the diode which is connected to the reference and wherein the other diode is directly connected to the output from the accelerometer.

11. in a switching device, an accelerometer for measuring acceleration, a decision circuit connected to the accelerometer, the decision circuit including a pair of diodes arranged to conduct in opposite directions, means connecting the output of the accelerometer to one of the diodes, means supplying a reference to the other of the diodes, means for establishing a complete circuit for the diodes, the diode with the higher voltage applied thereto conducting current and the other diode with the lower voltage applied thereto beingnonconducting, said means supplying a reference including means connected to said other diode capable or" assuming conducting and'nonconducting states, said means being normally nonconducting when current is not passing through said other diode and being conducting when current is passing through said other diode, integrating means connected to said decision means and serving to generate a ramp function when the output from the accelerometer passes the reference, and Zero comparator means for comparing said ramp function with said reference to determine when said ramp function passes said reference, and switching means actuated by said zero comparator as said ramp function passes said reference.

12. In a switching device, a servo accelerometer inciuding means for supplying a restoring current, a decision circuit connected to the accelerometer and comprising rst and second diodes, means connecting the output of the accelerometer to the iirst diode, a transistor having base, emitter and collector elements, means connecting the base element to the second diode, eans Vfor biasing the transistor to place a predetermined reference voltage on the base of theA transistor, means for forming a path for current fl w frornthe first and second diodes, the diodes facing in opposite directions so that current can ow only in one diode at a time, an integrator circuit connected to the decision circuit, the integrator circuit consisting of a transistor having base, collector and emitter elements, a capacitor connected between the collector and base elements of the last named transistor, means connecting the base element of said last named transistor to the collector of the transistor in the decision circuit, and zero comparator means connected to the .integrator circuit, the zero comparator means comprising rst and second diodes, the diodes facing in opposite directions so that the current can only low in one diode at a time, means for establishing current iiow through the diodes, means for applying said reference voltage to one of the diodes, and means for connecting the other of the diodes to the collector of said last named transistor, and switching means connected to the Zero comparator.

l 13. A switching device as in claim l2 together with amplier means connected between the zero comparator and the switching means.

14. A switching device as in claim 12 together with means connected to the accelerometer ermitting an increase in the restoring current flow in the accelerometer when the output of the accelerorneter exceeds a value which is equal to the output of the reference means, said 1 last named means including a serially connected resistor and. diode.

15, A switching device as in cia-im 12 together with a power supply and regulator, said power supply and regulator including a transistor having base, collector and emitter elements, a Zener diode connected to the base of the transistor, a Zener diode connected to the emitter of the transistor, a D.C. voltage supply, and means connecting the D.C. voitage supply to the collector of the transistor.

16. In a switching device, means for measuring acceleration producing an output voltage, reference means producing a voltage representing a predetermined switching point, decision means for determining when the output voltage from the means for measuring acceleration reaches and passes the output voltage of the reference means, an interator connected to the output of the de cision means, a zero comparator connected to the output 1&1 of the integrator, and switching means connected to the output of the zero comparator.

17. A switching device as in claim 16 wherein the means for measuring acceleration is a servo accelerometer including means for supplying a restoring current together with means connected to the accelerometer for permitting an increase in current ow in the accelerometer when the output voltage of the accelerometer exceeds a value which is equal to the voltage output of the reference means.

References Cited in the tile of this patent UNITED STATES PATENTS 2,554,512 Varian May 29, 1951 2,613,071 Hansel Oct. 7, 1952 2,726,071.1 Ketchledge Dec. 6, 1955 2,775,724 Clark Dec. 25, 1956 3,012,180 Finvoid Dec. 5, 1961 3,036,241 Zelina May 22, 1962 

12. IN A SWITCHING DEVICE, A SERVO ACCELEROMETER INCLUDING MEANS FOR SUPPLYING A RESTORING CURRENT, A DECISION CIRCUIT CONNECTED TO THE ACCELEROMETER AND COMPRISING FIRST AND SECOND DIODES, MEANS CONNECTING THE OUTPUT OF THE ACCELEROMETER TO THE FIRST DIODE, A TRANSISTOR HAVING BASE, EMITTER AND COLLECTOR ELEMENTS, MEANS CONNECTING THE BASE ELEMENT TO THE SECOND DIODE, MEANS FOR BIASING THE TRANSISTOR TO PLACE A PREDETERMINED REFERENCE VOLTAGE ON THE BASE OF THE TRANSISTOR, MEANS FOR FORMING A PATH FOR CURRENT FLOW FROM THE FIRST AND SECOND DIODES, THE DIODES FACING IN OPPOSITE DIRECTIONS SO THAT CURRENT CAN FLOW ONLY IN ONE DIODE AT A TIME, AN INTEGRATOR CIRCUIT CONNECTED TO THE DECISION CIRCUIT, THE INTEGRATOR CIRCUIT CONSISTING OF A TRANSISTOR HVING BASE, COLLECTOR AND EMITTER ELEMENT, A CAPACITOR CONNECTED BETWEEN THE COLLECTOR AND BASE ELEMENTS OF THE LAST NAMED TRANSISTOR, MEANS CONNECTING THE BASE ELEMENT OF SAID LAST NAMED TRANSISTOR TO THE COLLECTOR OF THE TRANSISTOR IN THE DECISION CIRCUIT, AND ZERO COMPARATOR MEANS CONNECTED TO THE INTEGRATOR CIRCUIT, THE ZERO COMPARATOR MEANS COMPRISING FIRST AND SECOND DIODES, THE DIODES FACING IN OPPOSITE DIRECTIONS SO THAT THE CURRENT CAN ONLY FLOW IN ONE DIODE AT A TIME, MEANS FOR ESTABLISHING CURRENT FLOW THROUGH THE DIODES, MEANS FOR APPLYING SAID REFERENCE VOLTAGE TO ONE OF THE DIODES, AND MEANS FOR CONNECTING THE OTHER OF THE DIODES TO THE COLLECTOR OF SAID LAST NAMED TRANSISTOR, AND SWITCHING MEANS CONNECTED TO THE ZERO COMPARATOR. 